Redington Mountain Wind Farm -...

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System Impact Study Redington Mountain Wind Farm 90 MW Capacity Final Report Central Maine Power System Planning January 10, 2006 Principal Contributor Kristin Kerr

Transcript of Redington Mountain Wind Farm -...

Page 1: Redington Mountain Wind Farm - maine.govmaine.gov/dacf/lupc/projects/windpower/redington/Documents/Secti… · 1. Introduction 7 2. Interconnection of Redington Mountain Wind Farm

System Impact Study

Redington Mountain Wind Farm

90 MW Capacity

Final Report

Central Maine Power System Planning

January 10, 2006

Principal Contributor Kristin Kerr

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Table of Contents

Executive Summary 5 Interconnection Requirements and Cost Estimates 1. Introduction 7 2. Interconnection of Redington Mountain Wind Farm 7 3. Generator Information 8 3.1 Vestas Model V90 4. Steady State Criteria 8 Pre-Contingency Post-Contingency 5. Base Case Development 13 5.1 Steady State Base Case 14 5.2 Transient Base Case 17 5.3 Transient Dispatch Conditions 17 5.4 Transient Sensitivity Analysis 18 Y-138 & NRI Sensitivity Case Modifications 18

Light Western Maine Generation Sensitivity 20

6. Steady State Contingencies 21 6.1 Line Outage (N-2) Steady State Testing 22 6.2 Relevant Special Protection Systems (SPSs) 23 Saco Valley Undervoltage SPS Winslow –SD Warren Undervoltage SPS

7. Steady State Analysis Results 24 7.1 Pre-Project (Phase I at 30 MW) Results 24 7.2 Initial 90 MW Redington Mountain Wind Farm post-project results 24

7.3 Final 90 MW Redington Mountain Wind Farm post-project results, with Reactive Reinforcements 25 7.4 Kennebec River 345 kV Double Circuit Tower Contingency 26

8 Steady State Sensitivity Analysis Results 27 8.1 Northeast Reliability Interconnect (NRI) Project 27

Dispatch Results

8.2 Y-138 Line Closing Project 28 Dispatch Results

8.3 Upper Kennebec Dispatch Sensitivity 28

8.4 Livermore Falls Stuck Breaker Sensitivity 29

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9 Transient Performance Criteria 31 9.1 Contingencies 31 Normal Contingencies Extreme Contingencies Oscillatory Response 9.2 Bulk Power System Testing 33 9.3 Short Circuit Analysis 33

10. Transient Analysis Study Methodology 34 10.1 Fault Contingency Descriptions 34

11. Transient Analysis Results 36 11.1 Three-phase Fault Results 36 11.2 Single Line-to-Ground Fault Results 38 Voltages Angles

12. Transient Sensitivity Analysis Results 39 12.1 Northeast Reliability Interconnect (NRI), and Y-138 Line Closing 39 12.2 Light Western Dispatch 40

13. Short Circuit Protection 41 13.1 Protection Analysis 42 Protection Summary Protection Recommendations

14. Conclusions and Recommendations 43

Appendix A: Vestas V90 Electrical Data Appendix B: Steady State One-Line Diagrams (on CD) Appendix C: Steady State Case Summaries: Load, Generation, & Transfers Appendix D: Exception Reports for Contingencies Appendix E: Transient Case Summaries: Load, Generation, & Transfers Appendix F: Advanced Grid Option 2, V90 VCRS-3.0 MW Low Voltage Ride Through for the Vestas V90 Appendix G: Modeling the Vestas V90 Wind Turbine in PSLF-Version 1 Appendix H: Transient One-Line Diagrams, Voltage, Angle & GCX Plots Appendix I: “Redington Mountain Wind Farm System Impact Study – Phase I”

Final Report, November 5, 2003

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Figures & Tables Figure 1: Planned Location of Redington Mountain Wind Farm 9 Figure 2: Planned Interconnection of Redington Mountain Wind Farm 10

to Bigelow S/S Figure 3: CMP Western Area 115 kV Transmission 11 Figure 4: Redington Mountain Wind Farm One Line Diagram 12 Table 5-1: Summary of Steady State Base Cases 16 Table 5-2: Interface Transfer Summary 17 Table 5-3: Major Generator Conditions with ME-NH Interface at 1700 MW 18 Table 5-4: Major Generator Conditions with ME-NH Interface at 1400 MW 18 Table 5-5: Interface Transfer Summary with NRI, Y-138 and Redington 19 Projects in Service Table 5-6: Major Generator Conditions with NRI, Y-138 and Redington 20 Projects in Service Table 5-7: Light Western Maine Generation Summary 20 Table 6-1: 115 kV Line Contingencies 21 Table 6-2: Autotransformer Contingencies 22 Table 6-3: Stuck Breaker Contingencies 22 Table 6-4: 345 kV Line Contingencies 22 Table 6-5: 345 kV Stuck Breaker Contingencies 22 Table 6-6: 345 kV Double Circuit Tower Contingency 22 Table 7-1: Comparison of Voltage Performance Peak 83 Case with Maxcy’s 115 kV Stuck Breaker KT3L-1 Outage 25 Table 8-1: NRI Generation Dispatch Comparison 26 Table 8-2: NRI Voltage Results 26 Table 8-3: Western Maine Steady State Generation 27 Table 8-4: Upper Kennebec Generation Sensitivity 28 Table 8-5: Upper Kennebec Dispatch Voltages 28 Table 8-6: Livermore Falls Stuck breaker Sensitivity 29 Table 10-1: Transient Contingency Summary – Three Phase Faults 34 Table 10-2: Transient Contingency Summary – Single Line-to-Ground Faults 35 Table 11-1: Transient Three Phase Fault Result Summary 37 Table 11-2: Transient, Section 357, Three Phase Fault Result Summary 37 Table 11-3: Transient Single Line-to-Ground Fault Result Summary 38 Table 12-1: Transient Fault Contingency Summary - NRI and Y138 Sensitivity 39 Table 12-2: Transient Fault Contingency Summary – 40 Light Western Maine Dispatch Sensitivity Table 13-1 Short Circuit Fault Study 41

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Executive Summary Endless Energy has proposed a 90 MW wind farm, consisting of multiple Vestas V90 3 MW wind turbine-generators located on the Black Nubble and Redington Mountain Ranges in Redington, Maine. This location is in the mountains of northwest Maine, near the CMP 115 kV transmission system emanating from the upper Kennebec River generation, and distant from the Maine 345 kV system (see Figure 1 for the location of this generation project relative to the Maine transmission system). The 90 MW generation project is known as Redington Mountain Wind Farm. The in-service date for this project is now anticipated to be early 2007. For the steady state portion of this study Redington Mountain Wind Farm is dispatched against the Wyman and Harris hydroelectric generation on the upper Kennebec River. To provide reasonably stressed system conditions for this study, system conditions were modeled and area generation was maximized so that either 115 kV Section 63, Section 66, or Section 83 is loaded to its rating, either its normal rating in the base case, or its Short-Term Emergency (STE) rating following the loss of any other line section. A total of twelve steady state base cases that reflected different reasonably stressed system conditions were developed. The initial Redington 90 MW project base cases show bus voltages at Wyman Hydro 1.5% lower in the light load cases and 2% to 3.5% lower in the peak load cases, compared to the pre-project base cases. Each of these twelve base cases was tested with a total of 50 contingencies. Test results indicate that there were several contingencies that resulted in unacceptably low voltages, all located in the Waterville-Winslow-Skowhegan area, and in Guilford. With a total of 45 MVAR of capacitor additions at Winslow, Lakewood, Guilford and Sturtevant (23 MVAR is CMP’s responsibility, and 22 MVAR is Redington’s responsibility), all 50 contingencies for all base system conditions resulted in acceptable performance with the Redington Mountain Wind Farm, with and without the NRI and Y138 projects. The transient cases represent a stressed Northwestern area export, specifically around Wyman Hydro. In the pre-Redington project cases, Wyman Hydro, Harris, Williams and Stratton Energy Associate (SEA) generators are on at full output. In the post-Redington project cases, Redington generation is dispatched against Harris and Wyman Hydro. With most other Maine generation ON, AEI Livermore Falls and two out of the three Androscoggin Energy Center (AEC) units were turned off in order to achieve maximum interface flows. These conditions were used for all faults with the exception of a three-phase normally closed fault at Buxton on Section 385, and a three-phase stuck-breaker fault at West Medway on Section 357. Both of these contingencies resulted in an unstable system response with the Maine–New Hampshire interface at 1,700 MW. This is consistent with the results obtained in the “Y138 Closing Study.” CMP and ISO New England are separately investigating ME-NH interface limits with W. F. Wyman unit #4 on-line. The interface was reduced to approximately 1,400 MW to enable an acceptable system response. Discussions with ISO-New England validated the 1,400 MW ME-NH interface transfer as acceptably stressed under these conditions. In addition, two sensitivity cases were analyzed for transient stability. Analysis with both the NRI and Y138 Closing Project in service, showed there were no adverse effects on the interconnection of the 90 MW wind farm, nor does the wind farm have any adverse effect on the system performance with these projects. The Light Western Maine Dispatch sensitivity was conducted to evaluate the Low Voltage Ride Through (LVRT) capabilities of the Vestas V90 turbine generators when there was less generation in the area to sustain local voltages. Although for the three-phase fault cases, the post-fault voltage dipped lower than cases with more generation dispatched in the immediate area, the ride-through capability of the generator met the LVRT criteria. Protection analysis revealed that in order for the Section 215 line rating to increase to the 212°F limit of approximately 135 MVA, the relaying must changed from overcurrent to step distance/directional

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ground overcurrent. To provide high speed and dedicated fault clearing for Section 215, the backup overcurrent protection on the K63-1 breaker must be removed and Section 215 connected to the Wyman Hydro bus through a new 115 KV breaker. The existing transfer trip carrier that trips the Stratton Energy plant for K215-1 opening must be modified to include a trip of the Redington Wind Farm generation and a 115 KV breaker added at Bigelow Substation to connect the Redington Wind Farm site. The Redington 115/34.5 KV transformer should be provided with CMP’s standard protection package for a transformer of this size and voltage, which is primary transformer differential and backup high-side overcurrent. Interconnection Requirements and Cost Estimate The study resulted in the following interconnection requirements for Redington Mountain Wind Farm with the corresponding estimated cost: Endless Energy Responsibility - $3,200,000

• Bigelow Substation: Expand yard, add a 115 KV bus, breaker, and control house - $1,510,000

• Wyman Substation: Separate Section 215 from 63, terminate with a breaker - $660,000 *

• Section 215 Transmission Line: Re- rate to 212o F - $300,000

• Lakewood Substation: Add a new 10.8 MVAR capacitor bank - $370,000

• Guilford Substation: Expand the existing 5.4 MVAR capacitor bank to 10.8 MVAR - $140,000

• Sturtevant Substation: Add a new 5.4 MVAR capacitor bank. - $220,000

* This amount includes a credit of $50,000, the cost to replace the existing over-dutied circuit switcher K215-1.

CMP Responsibility • Winslow Substation: Expand the existing capacitor bank from 9 MVAR to 16.2 MVAR • Winslow Substation: Add a new second 16.2 MVAR capacitor bank • Wyman Substation: subject to further review with accurate Harris & Wyman Hydro generator

models, replace breaker K63-1 Note that the Section 215 future normal summer 212° F rating of 135 MVA may limit Redington (90 MW) and SEA (47 MW) with a very light load at Bigelow Substation. With these interconnection requirements, the Redington Mountain Wind Farm meets the ISO New England Reliability Standards and the Minimum Interconnection Standard; and. the interconnection causes no significant adverse impact to the NEPOOL bulk power system. There are no relevant queued resources ahead of Redington Mountain Wind Farm.

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Redington Wind Farm 90 MW System Impact Study Page 7 January 10, 2006

1. Introduction Endless Energy has proposed a 90 MW wind farm, consisting of multiple Vestas V90 3 MW wind turbine-generators located on the Black Nubble and Redington Mountain Ranges in Redington Maine. This location is in the mountains of northwest Maine, near the CMP 115 kV transmission system emanating from the upper Kennebec River generation, and distant from the Maine 345 kV system (see Figure 1 for the location of this generation project relative to the Maine transmission system). The 90 MW generation project is known as Redington Mountain Wind Farm. A System Impact Study for the Redington Mountain Wind Farm ‘Phase I’ project, with a proposed 30 MW total capacity was completed in November 2003. Utilizing the Vestas V90 turbine, Redington Mountain Wind Farm will connect to the Central Maine Power (CMP) transmission system under the ISO New England Minimum Interconnection Standard. The in-service date for this project is now anticipated to be early 2007.

2. Interconnection of Redington Wind Farm A new Endless Energy Electric Harvest (a.k.a. Nash Stream) Substation will be constructed and connected to Central Maine Power’s Bigelow Substation by an 8.2-mile 115 kV transmission line. The new substation will include two parallel step-up 34.5/115 kV Delta-Wye 37.5/50/62.5 MVA transformers (Z = 8.5% on transformer base). Two 34.5 kV generator lead circuits will extend 1.0 mile and 2.1 miles to the Black Nubble and Redington Pond Range turbine regions, respectively. The 34.5 kV circuits then will extend between the turbines through underground cabling for 2.0 miles, and 1.5 miles with a half-mile spur, respectively. Several figures provide maps and diagrams to indicate how the Redington Wind Farm project interconnects with the Maine transmission system: • Figure 1 geographically illustrates the location and interconnection of the proposed Redington

Mountain Wind Farm in the Maine transmission system. • Figure 2 geographically illustrates the location and interconnection of the proposed Redington

Mountain Wind Farm in local detail, showing the substation and individual turbine-generator locations.

• Figure 3 is a one-line diagram that illustrates the proposed generation in relation to the northwestern CMP 115 kV transmission system. Note that the area in which the Redington Mountain Wind Farm is located is a generation-rich exporting area, and boundaries for the “Wyman Hydro Export” and “Northwestern Maine Export” areas are shown on the one-line diagram.

• Figure 4 is a one-line diagram that illustrates the proposed generation in relation to the local CMP 115 kV transmission system around Wyman Hydro, with both current and proposed breaker configurations. Section 215 must connect directly to the Wyman Hydro 115 kV bus with a circuit breaker to provide adequate system protection.

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3. Generator Information Two turbine site locations are planned for the Redington Mountain Wind Farm. The Vestas Model V90 wind turbine-generators were modeled by using two equivalent aggregate generators at the two collector sites along the Black Nubble & Redington Pond Range turbine regions. 3.1 Vestas Model V90 The Vestas V90 is a 3.0 MW unit that utilizes a variable-speed wound-rotor induction generator, rated at 1000V line-to-line. The V90 has a microprocessor control unit that adjusts the current in the rotor circuit of the generator, which gives precise control of the reactive power. The reactive power capability is between 96% inductive and 98% capacitive at full output. The V90 has an “OptiTip” microprocessor pitch control system, which continuously positions the blades’ pitch angle. This study models the Vestas V90 units as two aggregate 45 MW generators, each with a reactive range of –13 to 9.1 MVAR, controlling the generator terminal bus voltage to 105%. The Vestas V90 Electrical Characteristics document with control system description is in Appendix A of this System Impact Study report.

4. Steady State Criteria Impacts due to Redington will be noted by the normal pre-contingency and post-contingency performance criteria that are defined by the following: Pre-Contingency • Acceptable branch loadings are less than 100% of the Normal summer rating, • Acceptable bus voltages are in the range, 0.95 <= Vpu <= 1.05. Post-Contingency • No branch loadings can exceed 100% of the Short-Term Emergency (STE) summer ratings, • Branch loadings greater than the Long-Term Emergency rating (LTE) and less than STE must be

reduced to LTE in 15 minutes, • Acceptable bus voltages are in the range, 0.95<= Vpu <= 1.05.

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Figure 1:Planned Location of

Redington Mountain Wind Farm

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BigelowSubstation

Figure 2:Planned Interconnection ofRedington Mountain Wind

Farm to Bigelow S/S

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RPA

RUMFORD INDUSTRIAL PARK

K228/T1HK217/228

KGBS/229K229/217

KT1H/GBS

T1

K218-1K228-1

MEADK211-1

T3H

T4H

T2

RUMFORD

WOODSTOCK

Sect

228

Sect

217

Sect

211

Sect 218

Sect 229

HARRISON

TOSACO VALLEY

(PSNH)

Sect

210

Sect

214

RILEY

INT'LPAPER

AEC

Sect

230

Sect

227

K230-1 K227-1

K227-2K230-2

K229-1 K89-2

K217-1 K210-1 K87-2

K209-2K214-1KIMBALLROAD

Sect 87

Sect

209

LIVERMOREFALLS

K89-1

GULFISLAND

Sect

200

STURTEVANT

RAYMOND

Sect 89

CMP WESTERN AREA115 KV TRANSMISSION

T1

T1

Sect 208

HOTELROAD

LEWISTONLOWER

CROWLEYS

K63-2

K200-4

AEI

Sect 200A

K208-1

NORWAY

T1

K62-2

K64-2

K166-1

K81-3

K167-1

K69-4

K62/81

K64/167

K166/69

KB2/CAP

SUROWIEC

Sect 62

Sect 201

Sect

202

Sect 75

Sect 61A Sect 61

Sect

61

Sect 64

Sect

63

Sect 63B

Sect 63

TOBOWMANSTREETSect 212

LOVELLT2

COGEN

#2 STEAM

#1 GAS

#1G

AS

#2G

AS

#3G

AS

208-

2

209-

1

K62-1

K201-2

K202-1

K202-2

K75-175-2

K61A-2

K64-1

K201-1

K61-1

K200-1

K212-1

K200A-3

TO TOPSHAM

TOTOPSHAM

TOSPRING ST

TOS167A TAP &

MOSHERS

Sect

167

Sect

69

Sect

166

Sect

81

K87-1 61-4

50 MVAR

50 MVAR

50 MVAR

KT1L

KT1H

T1

T4

T5

T1

T3T1

T2

T1

T2

T1 T2

T1

T2

T1 T2

T1

210-2

211-2

MADISONPAPER

40 MVAR40 MVAR

RUMFORD/JAY AREAEXPORT

ANSONHYDRO

ABENAKIHYDRO

K63A-2

WILLIAMSHYDRO

#1

#2

Sect 63A Sect 63C

EMBDEN

BIGELOW

SEAK215A-4

K63-1 K83-5 K66-1

K222-1

WYMANHYDRO

Sect 222ACONUS

#1 #2 #3 #4

HARRISHYDRO

KT1HLAKEWOOD

Sect 83B

Sect

222

K83C-2

Sect

83C

SAPPISOMERSET

GORBELL

K66A-1

Sect

66A

HARTLANDK66-6

K85-1 K203-1

K67-1

TOMAXCY'S

Sect

67Sect 66

DETROIT

Sect

85

GUILFORD

TOBUCKSPORT

KT2H

KT1H KT3HK83-1

K84-1

TOMAXCY'S

WINSLOW

Sect

84

S ect 83

Sect

203

KT2H

Sect 215

Sect

215A

NORTHWESTERNMAINE EXPORT

INTERFACE

K215-1

......

REDINGTON WIND

WYMAN HYDROEXPORT

New

Nash Stream#1 #2 #3

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Harris Hydro

G1, G2, & G3

KG1 KG2 KG3

G1 G2 G3

Wyman Hydro

Sec

222

K215A

-4

RedingtonMountain Wind

Farm

Big

elow

Stratton Energy

K215-1K63-1

Sec 215

Sec 63

G1 & G2

K63A-2WilliamsStation

Madison PaperMisc. Hydros

Stur

teva

nt

Livermore Falls

K63-2

Sec

63

Har

tland

Detroit

K66-6

G1

Gorbell

Sec 66

Sec 66

K66-1K83-5

K222-1

Lake

woo

d

KT1

H

K83C-2

Scott Paper

G1 & G2

Winslow

K83-1

Sec

83

Sec

83

Sec 83B

Sec 83CSec 63B

Sec 63A

Emde

n

Sec 63C Sec 66A

Sec

63

Redington Mountain Wind Farm

New

Figure 4:One Line Diagram Proposed

configuration

K215

-1

Current configuration

Black NubbleCollector Site

RedingtonMountain

Collector Site

Harris Hydro

G1, G2, & G3

KG1 KG2 KG3

G1 G2 G3

Wyman Hydro

Sec

222

K215A

-4

RedingtonMountain Wind

Farm

Big

elow

Stratton Energy

K215-1K63-1

Sec 215

Sec 63

G1 & G2

K63A-2WilliamsStation

Madison PaperMisc. Hydros

Stur

teva

nt

Livermore Falls

K63-2

Sec

63

Har

tland

Detroit

K66-6

G1

Gorbell

Sec 66

Sec 66

K66-1K83-5

K222-1

Lake

woo

d

KT1

H

K83C-2

Scott Paper

G1 & G2

Winslow

K83-1

Sec

83

Sec

83

Sec 83B

Sec 83CSec 63B

Sec 63A

Emde

n

Sec 63C Sec 66A

Sec

63

Redington Mountain Wind Farm

New

Figure 4:One Line Diagram Proposed

configuration

K215

-1

Current configuration

Black NubbleCollector Site

RedingtonMountain

Collector Site

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5. Base Case Development

Base cases were developed starting with the year 2007 ‘T1R’ peak load and ‘T1LTR’ light load cases used in the ‘Seabrook Uprate’ System Impact Study. These cases included the addition of the following future system enhancements:

a. Mystic 8 & 9 generation b. AES Londonderry generation c. Kendall 4 generation d. Chestnut Hill caps e. New Scobie autotransformer and 115 kV bus reconfiguration f. Cross Sound DC link g. Section G146 upgrade h. New Merrimack 230/115 kV transformer i. Series reactors on the S Agawam-N Bloomfield lines j. Central Mass. Upgrades including Wachusetts 345 kV Substation k. Third PAR at Waltham l. Line rating changes, series reactors, etc. in Boston area m. New Capacitors at Northboro Road and Millbury n. Shunt reactors at Scobie (for light load case) o. NH Seacoast changes including caps, addition of substations at Portsmouth,

Brentwood, and Great Bay, second transformer at Rochester and load estimates for 2007 peak

p. Crowley’s 50 MVAR capacitor bank

Additional updates to the base cases: q. Capacitor banks at Bridgton (modeled at Kimball Road), Lovell and Woodstock,

which will be in service in 2005. r. Turned off the Gorbell generator (interconnected to Section 66, Wyman-Detroit),

which was retired and dismantled in 2004. s. Western Maine peak loads were revised to conform to the 2004 NPCC library update,

which resulted in higher area loads in the peak load cases.

Minor revised line ratings and impedance changes for the new Redington Mountain Wind Farm project were modeled. These impedance changes were made to accommodate a wind turbine placement study for Endless Energy. Based on the recommendations of the Redington Mountain Wind Farm Phase I System Impact Study, the line rating of Section 215 (Wyman Hydro – Bigelow) was increased to its 477 KCM ACSR conductor ampacity of 135 MVA, from today’s 56 MVA summer normal rating. With these updates, the base cases are compliant with today’s OP-17 requirements. Interface definitions as found in the Interface Transfer Summaries do not include flows created by the NRI or Y138 project unless specifically noted in this report. The interfaces today are defined as follows: New Brunswick – Maine Section 396 Maine - New Hampshire Section 391 Section 197 Section 250 Section 385

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Sensitivities with the Y138 Closing Project in service will add flow to the Maine-New Hampshire interface from Saco Valley to the White Lake Phase Angle Regulator. Sensitivities with the NRI project in service will add flow from Point Lepreau to Orrington, Section 3016. 5.1 Steady State Base Case Three variations of the peak and light load base cases were created, to individually stress each of the three 115 kV lines (Sections 63, 66, and 83) emanating from Wyman Hydro. Flows on these lines are influenced not only by the generation (Redington, SEA, Harris, Wyman) at the top of the “tree” in the north (reference Figure 4), but also by generation and industrial load on or downstream of these lines, such as Madison Paper, Scott Paper (SAPPI SD Warren-Somerset), and Rumford/Jay area load and generation. Because of the influence of all of these factors, three separate dispatches were created to stress the flow on each line. Sections 63, 66, and 83 are limited as follows: • Section 63 (Wyman Hydro – Section 63A&C tap – Section 63B tap – Sturtevant – Livermore Falls):

Limiting Element Normal (MVA) LTE (MVA) STE (MVA) 160° F limited Coot 795 36/1 conductor 162.4 162.4 171.8 Breakers 175.3 188.0 266.1

• Section 66 (Wyman Hydro – Section 66A tap – Hartland – Detroit):

Limiting Element Normal (MVA) LTE (MVA) STE (MVA) Disconnect switches 143.4 164.9 193.6 160° F limited Coot 795 36/1 ACSR conductor 162.4 162.4 171.8

• Section 83 (Wyman Hydro – Section 83B tap – Section 83C tap – Winslow):

Limiting Element Normal (MVA) LTE (MVA) STE (MVA) 180° F limited conductor Pelican 477 18/1 ACSR 135.3 138.9 142.8 AB switches 143.4 164.9 193.6 Wave Traps 167.3 192.8 251.8 Breaker 175.3 188.0 266.1

Note that none of these 115 kV line sections is limited by its conductor ampacity (the thermal current-carrying capacity of the wire itself). Rather, the ratings are limited by either sag clearances at lower conductor temperatures or by terminal equipment. However, if sag clearances were increased or terminal equipment were replaced, additional reinforcements may be needed; due to increased flows and/or lower voltages. For the pre-project (Redington Phase I @ 30 MW) initial base case, each of the three dispatch scenarios was initially set up to maintain a high flow up to 100 % of the Normal rating of the 115 kV line section being stressed. The three sets of base cases are labeled: • Peak Load: ‘Peak 63,’ ‘Peak 66,’ and ‘Peak 83’ for maximum loading on the labeled line section

at peak system loads • Light Load: ‘Light 63,’ ‘Light 66,’ and ‘Light 83’ for maximum loading on the labeled line

section at light system loads

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Redington Wind Farm 90 MW System Impact Study Page 15 January 10, 2006

An initial contingency analysis was performed to confirm a secure dispatch under reasonably stressed system conditions for the initial base condition described above. Several loading and voltage issues were identified following this initial contingency analysis on the initial base cases. In order to obtain secure system conditions, the following dispatch changes were made: • The Rumford Power Associates (RPA) and Mead Cogeneration output was reduced in the ‘Light

66’ and ‘Light 83’ cases, to avoid an overload of Sections 208 and 209 (Kimball Road-Raymond-Surowiec), following a stuck breaker contingency at Gulf Island Substation.

• A single Wyman Hydro G1 generator was reduced or switched off in the ‘Peak 66’ and ‘Peak 83’ cases, to avoid an overload of Section 83 (Wyman-Lakewood tap), following a Section 66 outage or stuck breaker contingencies at Detroit and Gulf Island Substations.

• Androscoggin Energy Center G1, G2 & G3 output was reduced in the ‘Peak 66’ and ‘Peak 83’, and ‘Light 66’ and ‘Light 83’ base cases to avoid an overload on Section 89 (Riley-Livermore Falls), under all-line-in conditions.

Because the Redington pre-project (Phase I) base cases had northwestern Maine generation restricted to respect reliability criteria, it was determined that the Redington post-project base cases would have to be dispatched versus generation north of the “Wyman Export” interface shown in Figure 3. Since the Section 215 rating must be increased, and will avoid a dispatch tradeoff with Stratton Energy Associates (SEA) generation, Wyman Hydro and Harris were chosen as the plants to dispatch against Redington. It can be observed that the northwestern CMP 115 kV voltage profile is reduced with Redington Mountain Wind Farm generation replacing Wyman and Harris hydroelectric generation. By dispatching Wyman Hydro and/or Harris generation off-line with generation at Redington, this area loses some reactive support for which Redington, with its limited generator reactive capability at a more remote location, is not able to compensate. When comparing the pre-project base cases to the Redington 90 MW project cases, the bus voltages at Wyman Hydro are 1.5% lower in the light load cases and 2% to 3.5% lower in the peak load cases, as indicated in the one-line diagrams found in Appendix B. It is possible but not probable for dispatch restrictions to occur without Redington in service, and these restrictions are not significant. With the Redington 90 MW project however, the potential congestion in the Upper Kennebec area is more significant. Table 5-1: Summary of Steady State Base Cases summarizes base cases developed for the steady state portion of this study. Case summaries for these cases are included in Appendix C.

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Redington Wind Farm 90 MW System Impact Study Page 16 January 10, 2006

Table 5-1: Summary of Steady State Base Cases

Section 63 Stressed Section 66 Stressed Section 83 Stressed

Description (All units in MW)

red2

_lt63

0 V80

30

Ligh

t Loa

d / R

edin

gton

30 M

W

red2

_lt63

_V90

30

Ligh

t Loa

d / R

edin

gton

90 M

W

red2

_pk6

3_V8

030

Peak

Loa

d / R

edin

gton

30 M

W

red2

_pk6

3_V9

030

Peak

Loa

d / R

edin

gton

90 M

W

red2

_lt66

_V80

30

Ligh

t Loa

d / R

edin

gton

30 M

W

red2

_lt66

_V90

90

Ligh

t Loa

d / R

edin

gton

90 M

W

red2

_pk6

6_V8

030

Peak

Loa

d / R

edin

gton

30 M

W

red2

_pk6

6_V9

090

Peak

Loa

d / R

edin

gton

90 M

W

red2

_lt83

_V80

30

Ligh

t Loa

d / R

edin

gton

30 M

W

red2

_lt83

_V90

90

Ligh

t Loa

d / R

edin

gton

90 M

W

red2

_pk8

3_V8

030

Peak

Loa

d / R

edin

gton

30 M

W

red2

_pk8

3_V9

090

Peak

Loa

d / R

edin

gton

90 M

W

Modeled NEPOOL Load/Losses 12128 12134 27863 27868 12006 12011 27676 27682 12024 12031 27676 27669

NB-ME 695 695 695 695 696 696 695 695 696 696 696 696

Orrington-South 1096 1096 987 987 580 580 348 348 745 744 988 988

Wyman Hydro Export 178 171 223 217 157 151 191 185 180 173 174 167 Rumford / Jay Export 21 21 263 263 384 384 421 421 378 378 427 427

Northwestern Maine Export 126 119 373 366 485 479 536 529 468 460 491 483 Surowiec-South 1067 1060 740 734 938 932 265 258 1079 1072 825 833

ME-NH 1318 1311 1620 1613 1191 1185 1151 1144 1330 1322 1090 1099 NNE-Scobie+394 2393 2387 2900 3085 2280 2274 2679 2673 2401 2395 2579 2632

North-South 2862 2857 3022 3023 2748 2742 2630 2624 2871 2864 2579 2586 Boston Import 1839 1839 3342 3342 1834 1834 3322 3322 1839 1839 3320 3320

SEMA/RI Export 1667 1667 2353 2354 1667 1667 2355 2355 1667 1667 2355 2355 NE East-West 1628 1621 2812 2627 1512 1506 2396 2389 1638 1632 2340 2348

New York-New England 155 161 -1157 -1152 271 277 -770 -764 143 150 -716 -724

Inte

rfac

es

Phase II Import 0 0 2000 2000 0 0 2000 2000 0 0 2000 2000 Redington 30 90 30 90 30 90 30 90 30 90 30 90

Wyman Hydro 25 0 82 57 5 0 50 25 60 35 65 40 Harris Hydro 85 50 86 51 85 30 86 51 52 17 52 17

Sub-Total 140 140 198 198 120 120 166 166 142 142 147 147 Stratton Energy (SEA) 45 45 45 45 45 45 45 45 45 45 45 45

Williams Hydro 15 15 15 15 15 15 15 15 14 14 14 14 Madison Paper Net Load 35 35 35 35 35 35 35 35 35 35 35 35

Lakewood 7 7 9 9 7 7 9 9 7 7 9 9 SAPPI Somerset Net Load 20 20 20 20 20 20 20 20 55 55 54 54

Winslow 11 11 11 11 11 11 11 11 0 0 0 0 Gorbell 0 0 0 0 0 0 0 0 0 0 0 0

Guilford 70157 20 20 15 15 0 0 0 0 20 20 15 15 Maine Independence 1-3 523 523 523 523 0 0 0 0 166 166 523 523

Champion G3 65 65 65 65 65 65 65 65 65 65 65 65 Bucksport Energy G4 0 0 115 115 0 0 0 0 0 0 115 115

AEI 0 0 0 0 16 16 39 39 19 19 39 36 AEC 1-3 50 50 50 50 120 120 120 120 120 120 120 120

International Paper Net Load 47 47 47 47 7 7 9 9 13 13 2 2 RPA 1-2 0 0 0 0 235 235 266 266 235 235 266 266

Mead Paper Net Gen 30 26 25 25 44 44 75 75 44 44 75 75 Gulf Island 34 34 34 34 34 34 34 34 34 34 34 34

Lewiston Lower 47 47 47 47 47 47 47 47 46 46 47 47 W. F. Wyman 1-3 0 0 239 239 0 0 239 239 0 0 239 239 W. F. Wyman 4 0 0 622 620 0 0 622 622 0 0 0 0 Westbrook 1-3 438 344 531 531 344 344 531 531 344 344 531 531

Seabrook 1209 1209 1209 1209 1209 1209 1209 1209 1209 1209 1209 1209 Schiller 4-6 0 0 145 145 0 0 145 145 0 0 145 145 Newington 0 0 411 411 0 0 411 411 0 0 411 411

Are

a G

ener

atio

n / I

ndus

tria

l Loa

d

Con Ed Newington 338 338 533 533 338 338 533 533 338 338 533 533

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Redington Wind Farm 90 MW System Impact Study Page 17 January 10, 2006

5.2 Transient Base Case The base case for all transient analysis was created from the Seabrook Phase 1 System Impact Study, spring light load case representing the 2007 transmission system. That case has a NEPOOL system load of 11,980 MW, and is derived from the 2000 New England Loadflow library. This base case was modified to include the steady state interconnection requirements for the 90 MW Redington Mountain Wind Farm. A total of 45 MVAR of capacitor additions at Winslow, Lakewood, and Guilford Substations’ 34.5 kV busses are required to obtain acceptable performance for all system conditions which were tested. These reinforcements are reflected in the modified cases as follows:

• expand the existing capacitor bank from 9 MVAR to 16.2 MVAR at Winslow Substation • a second 16.2 MVAR capacitor bank at Winslow Substation • a 10.8 MVAR capacitor bank at Lakewood Substation • expand the existing 5.4 MVAR capacitor bank to 10.8 MVAR at Guilford Substation • a 5.4 MVAR capacitor bank at Sturtevant Substation.

5.3 Transient Dispatch Conditions The cases represent a stressed Northwestern area export, specifically around Wyman Hydro. Pre - project, Wyman Hydro, Harris, Williams and Stratton Energy Associate (SEA) generators are on at full output, disregarding the thermal constraints discussed in Section 5.1 above. Post-project, the 90 MW of generation is dispatched against Harris and Wyman Hydro. For both pre- and post-project cases, the W. F. Wyman 4 generator is dispatched at full output, in lieu of the Westbrook generator. With most other Maine generation ON, AEI Livermore Falls and two out of the three Androscoggin Energy Center (AEC) units were turned off, in order to achieve maximum interface flows as seen in Table 5-2: Interface Transfer Summary. The resulting dispatch is listed in Table 5-3, Major Generator Conditions with ME-NH Interface at 1700 MW. These conditions were used for all faults with the exception of a three-phase normally-cleared fault at Buxton on Section 385, and a three-phase-stuck breaker extreme contingency fault at Medway on Section 357. Both of these contingencies resulted in an unstable system response with the Maine–New Hampshire interface at 1,700 MW. This is consistent with the results obtained in the “Y138 Closing Study.” For these two faults, the interface was reduced to approximately 1,400 MW; which was the maximum the transfer for the Section 385 fault to result in a stable system response. The dispatch to obtain this transfer is listed in Table 5-4: Major Generator Conditions with ME-NH Interface at 1,400 MW. Discussions with ISO-New England validated the 1,400 MW ME-NH interface transfer as acceptably stressed under these conditions. Detailed transient case summaries: load, generation and transfers are attached in Appendix E. One-line diagrams of the transient and sensitivity base cases are in Appendix H. Table 5-2: Interface Transfer Summary

Interfaces

Transfer Limit (MW)

Redington Generation OFF

(MW)

Redington Generation ON

(MW) New Brunswick - Maine 700 699 699 Orrington - South *1200 1162 1162 Surowiec-South 1180 1173 Maine – New Hampshire **1700 1689 1682 Seabrook-South 1141 1141 Northern New England – Scobie + 394 2504 2499 North-South 3000-3400 3033 3031 East-West 2325 2319

Section 86 is within normal limits ** With Wyman unit # 4 ON

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Redington Wind Farm 90 MW System Impact Study Page 18 January 10, 2006

Table 5-3 Major Generator Conditions with ME-NH Interface at 1,700 MW

Generators Gross Capability

(MW)

Redington Generation OFF

(MW)

Redington Generation ON

(MW) Redington 90 0 90 Wyman 1-3 80 80 27 Harris 1-3 90 88 52 Williams 15 14 14 SEA - Stratton 47 43 43 AEI - Livermore 39 0 0 Mead Hydros 39 18 18 Mead Cogen 110 65 65 MIS 549 549 549 Bucksport 191 191 191 RPA 273 273 273 AEC 161 54 54 WF Wyman 1-3 239 182 182 WF Wyman 4 636 636 636 Westbrook 579 0 0 Table 5-4 Major Generator Conditions with ME-NH Interface at 1,400 MW

Generators Gross Capability

(MW)

Redington Generation OFF

(MW)

Redington Generation ON

(MW) Redington 90 0 90 Wyman 1-3 80 80 27 Harris 1-3 90 88 52 Williams 15 14 14 SEA - Stratton 47 43 43 AEI - Livermore 39 0 0 Mead Hydros 39 18 18 Mead Cogen 110 65 65 MIS 549 549 549 Bucksport 191 0 0 RPA 273 273 273 AEC 161 54 54 WF Wyman 1-3 239 57 57 WF Wyman 4 636 636 636 Westbrook 579 0 0 5.4 Transient Sensitivity Analysis A sensitivity analysis was performed to establish the transient effect that Redington Mountain Wind Farm has on the system with both the Y-138 Project and Northeast Reliability Interconnect (NRI, also known as the 2nd New Brunswick Tie) Project operational. In addition, a Light Western Generation sensitivity was performed to ensure that Redington Mountain Wind Farm meets the Low Voltage Ride Through (LVRT) requirements under these conditions. These sensitivity analyses were done using the same 2007 light load (11,980 MW) case.

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Redington Wind Farm 90 MW System Impact Study Page 19 January 10, 2006

Y138 & NRI Sensitivity Case Modifications The Y138 Closing Project is based on a model developed by Northeast Utilities and E/PRO Consulting, with the following facilities, which are referred to as the Y138 Line Closing Project: • Addition of +20/- 60° phase angle regulator on the Y138 Line at Saco Valley • Re-tension all 28 miles of Section 214 (Kimball Road to Saco Valley) to obtain the 212° F ratings

of the existing 795 kCM ACSR conductor, 185/226/241 MVA (summer) and 246/275/293 MVA (winter)

• Upgrade the Beebe Substation B112 terminal equipment (circuit breaker, disconnect switches, bus work and secondary equipment) to reach or exceed the conductor rating of the B112 transmission line, 129/138/160 MVA (summer) and 153/160/178 MVA (winter)

• Addition of two 115 kV breakers at Saco Valley on Y138 and K1214 Lines • A total of 60 MVARs of 115 kV capacitors at Kimball Road • At total of 22 MVARs of 115 kV capacitors at White Lake • Increase to 40 MVARs of 115 kV capacitors at Beebe The phase shifter was set to the allow the maximum flow on Section 214 so its flow reaches its 212°F conductor rating (185 MVA summer normal rating) by adjusting the Phase Angle Regulator (PAR) based on generation patterns between Maine and New Hampshire. The Northeast Reliability Interconnect (NRI) was modeled by simulating a new 345 kV single-circuit transmission line from Point Lepreau generation station in New Brunswick to the Orrington Substation in Maine. A 30 MVAR shunt capacitor bank was added on the 115 kV bus at Gulf Island Substation (the Kimball Road 30 MVAR capacitor is included in the Y138 project listing above). Series compensation on Section 388 from Orrington to Maxcys, equal to 50% of the impedance of Section 388 and 392, was simulated. The NRI project increases New Brunswick-Maine transfer capability from 700 MW to 1,000 MW. Therefore, generation in New Brunswick was increased by 300 MW, and one Maine Independence Station generator was dispatched off; in order to maintain Orrington-south interface transfers near the 1,200 MW limit. These modifications were made to the base cases with a Maine-New Hampshire interface of approximately 1,700 MW. Case Summaries for this sensitivity can be found in Appendix E. In the table below, additional flows have been added to account for the NRI and Y138 Closing Project.

Table 5-5: Interface Transfer Summary with NRI & Y138 & Redington Projects In-Service

Interfaces Limit (MW)

NRI, Y138 & Redington (MW)

New Brunswick - Maine *1000 1041 Orrington - South 1200 1239 Surowiec-South 1105

Maine – New Hampshire 1700 **1758 Seabrook-South 1135 NNE-Scobie+394 2466

North-South 3000-3400 3078 East-West 2376

* Valid with NRI in service. ** The transfer summary in the appendix does not reflect additional flows to account for the Y138 Closing Project in

service. The total ME-NH interface is the amount shown in the summary, 1616 MW, with an additional 142 MW to account for the closing of PSNH Line Y138.

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Redington Wind Farm 90 MW System Impact Study Page 20 January 10, 2006

Table 5-6: Major Generator Conditions with NRI, Y138 & Redington Projects In-Service

Generators Gross Capability

(MW) NRI, Y138 &

Redington (MW) Redington 90 90 Wyman 1-3 80 27 Harris 1-3 90 52 Williams 15 14 SEA 47 43 AEI 39 0 Mead Hydros 39 18 Mead Cogen 110 65 MIS 549 274 Bucksport 191 191 RPA 273 273 AEC 161 54 WF Wyman 1-3 239 182 WF Wyman 4 636 636 Westbrook 579 0

Light Western Maine Generation Sensitivity Using the transient base case with Redington Mountain Wind Farm 90 MW project in service, and a Maine-New Hampshire interface flow of approximately 1,700 MW, generation in the upper Kennebec River area was reduced. The generation dispatch was based on actual conditions of June 12 to 14 of 2005. Table 5-7: Light Western Maine Generation Summary compares the generation in the upper Kennebec River. A complete case summary for this sensitivity can be found in Appendix E. Table 5-7: Light Western Maine Generation Summary

Generators

Gross Capability

(MW) Base Case

(MW)

Light Generation

(MW) Redington 90 90 90 Wyman 1-3 80 27 14 Harris 1-3 90 52 1.5 Williams 15 14 14 SEA 47 43 0 This sensitivity case was developed to ensure that the wind turbine-generators are able to sustain the local voltage in the absence of other significant generation in the same area, and not mask any low voltage ride-through issues that could occur with the wind farm.

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Redington Wind Farm 90 MW System Impact Study Page 21 January 10, 2006

6. Steady State Contingencies Contingency analysis was performed to confirm a secure dispatch under reasonably stressed system conditions for the pre-project base condition and determine system behavior with the Redington Mountain Wind Farm 90 MW project, and determine any additional interconnection requirements for the 90 MW project. Redington Mountain Wind Farm 90 MW interconnection results must satisfy ISO New England Planning Procedure PP-5-6, Scope of Study for System Impact Studies Under the Minimum Interconnection Standard and Enhanced Interconnection. All power flow analysis was performed using General Electric’s PSLF power flow simulation software. The same contingencies were analyzed as for the Redington Mountain Wind Farm Phase I System Impact Study, and are listed below. Table 6-1: 115 kV Line Contingencies Type # Name Description Line 1 Sect 89 Riley – Livermore Falls Line 2 Sect 229 Riley – Rumford I.P. Line 3 Sect 228 Rumford I.P. – Rumford Line 4 Sect 211 Rumford – Woodstock Line 5 Sect 210 Woodstock – Kimball Rd Line 6 Sect 210 & 211 Rumford – Woodstock – Kimball Rd Line 7 Sect 217 Rumford I.P. – Kimball Rd Line 8 Sect 87 Kimball Rd – Norway Line 9 Sect 209 Kimball Rd – Raymond Line 10 Sect 208 Raymond – Surowiec Line 11 Sect 208 & 209 Surowiec – Raymond– Kimball Rd Line 12 Sect 61 /61A Norway – S61A Tap – Gulf Island / S61A Tap – Hotel Rd Line 13 Sect 75 Hotel Rd – Lewiston Lower Line 14 Sect 202 Lewiston Lower – Crowley’s Line 15 Sect 201 Crowley’s – Gulf Island Line 16 Sect 212 Gulf Island – Bowman St Line 17 Sect 200 Livermore Falls – S200A Tap - Gulf Island / S200A Tap – AEI Line 18 Sect 64 Gulf Island – Surowiec Line 19 Sect 62 Crowley’s – Surowiec Line 20 Sect 63

/63A/63B Livermore Falls – Sturtevant – S 63B Tap – Williams – Wyman Hydro / S 63B Tap – Madison Paper

Line 21 Sect 81 Mason – Topsham – Surowiec Line 22 Sect 69 Bath – Topsham – Surowiec Line 23 Sect 166 Surowiec – Spring St Line 24 Sect 167 Surowiec – S167A Tap – Moshers / S167A Tap – Prides Corner Line 25 Sect 203 Bucksport – Detroit Line 26 Sect 67 /67A Maxcy’s – S 67A Tap – Detroit / S 67A Tap – Rice Rips Line 27 Sect 84 Maxcy’s – Winslow Line 28 Sect 66 Wyman Hydro – Gorbell – Hartland – Detroit Line 29 Sect 83 Wyman Hydro – S 83 B Tap – S 83 C Tap – Winslow / S 83 B Tap –

Skowhegan / S 83 C Tap – SAPPI Somerset

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Redington Wind Farm 90 MW System Impact Study Page 22 January 10, 2006

Table 6-2: Autotransformer Contingencies Type # Name Description Auto 1 Surowiec T1 Loss of Surowiec Autotransformer T1 Auto 2 Maxcy’s T1 Loss of Maxcy’s Autotransformer T3 Auto 3 Mason T1 Loss of Mason Autotransformer T9 Table 6-3: 115 kV Stuck Breaker Contingencies Type # Name Description StkB 1 Detroit Any SB Loss of Sections 66, 85, 67, 203, Detroit load StkB 2 Winslow Any SB Loss of Sections 84, 83, Winslow load StkB 3 Livermore Falls Any SB Loss of Sections 89, 63, 200, Livermore Falls load StkB 4 Gulf Island Any SB Loss of Sections 61, 64, 201, 212, 200, AEI gen StkB 5 Maxcy’s KT3L-1 SB Loss of Sections 60, 80, 67, Maxcy’s load, Auto T3, caps StkB 6 Maxcy’s KT3L-2 SB Loss of Sections 88, 68, 84, Auto T3 StkB 7 Bucksport KBS1/2 SB Loss of Sections 203, 205, 86, 65, Champion Paper,

Bucksport Energy gen, Bucksport load Table 6-4: 345 kV Line Contingencies Type # Name Description 345L 1 Section 375 Maine Yankee – Buxton 345L 2 Section 377 Maine Yankee – Surowiec 345L 3 Section 374 Surowiec – Buxton 345L 4 Section 385 Buxton – Deerfield 345L 5 Section 391 Buxton – Scobie Table 6-5: 345 kV Stuck Breaker Contingencies Type # Name Description 345B 1 Surowiec Any SB Loss of Sections 374, 377, autotransformer T1 345B 2 Scobie 9126 Loss of Sections 391, 326 345B 3 Deerfield 785 Loss of Sections 385, 307 345B 4 Deerfield 851 Loss of Sect 385, Deerfield autotransformer 345B 5 Deerfield 72 Loss of Sections 307, 373 Table 6-6: 345 kV Double Circuit Tower Contingency Type # Name Description 345D 1 DCT Sect 375/377 Loss of Sections 375, 377, Maine Independence Station

and Bucksport Energy generation Contingencies involving 345/115 KV autotransformers maintained the 115 KV capacitors on-line, if they were not removed by fault protection or their automatic controls.

6.1 Line Outage (N-2) Steady State Testing N-2 steady-state testing was not a part of this study, as the 90 MW of generation proposed in this project is not likely to cause greater than 1,200 MW loss-of-source under line outage conditions. Prior Maine generation System Impact Studies have shown less than 1,200 MW loss-of-source in their N-2 steady-state analysis.

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Redington Wind Farm 90 MW System Impact Study Page 23 January 10, 2006

6.2 Relevant Special Protection Systems (SPSs) Saco Valley Undervoltage SPS CMP today supplies the Conway area of New Hampshire radially by its interconnection of Section 214 (Kimball Road to Harrison to Lovell to Saco Valley) with Public Service Company of New Hampshire. If the Saco Valley 115 kV voltage falls below 94% for 4 seconds, then all feeder loads at PSNH Saco Valley and Intervale Substations are tripped. Winslow-SD Warren Undervoltage SPS If the Winslow 115 kV voltage on Section 83 falls below 96%, then SAPPI SD Warren-Somerset load is shed, such that the net flow into the mill is reduced to below 40 MW from above 40 MW. If Section 83C flow is less than 40 MW into the mill, no load is shed. Load is shed in multiple blocks, by opening feeder breakers. Each stage is cumulative, if additional load is still required to be shed: a) always first stage, approximately 4 MW b) either 10 – 15 MW, or 20 – 25 MW, depending on order schedule c) the ‘other’ load from either of the two blocks in (b) above d) last stage, 28 – 32 MW, effectively shuts down all paper machines The total duration of the four blocks of load shedding in this SPS can take up to 10 minutes. CMP is pursuing an automated scheme to speed operation of this SPS.

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Redington Wind Farm 90 MW System Impact Study Page 24 January 10, 2006

7. Steady State Analysis Results 7.1 Pre-Project (Phase I at 30 MW) Results The northern part of Section 86 from Bucksport to Belfast in the ‘Peak 63’ base case is slightly overloaded with a pre-contingency flow of 1% above its normal rating. This loading indicates that the Orrington-South interface is at its transfer limit. In the same ‘Peak 63’ case, Section 250 is as much as 19% above its STE rating and Section 197 is 1% above its STE rating following the 345 Deerfield 851 stuck breaker contingency. Section 250 reaches its STE rating following the 345 Scobie stuck breaker contingency in the same ‘Peak 63” case. These loadings indicate that the Maine-New Hampshire transmission interface is stressed beyond its transfer limit. Bus voltages in the light load cases and the ‘Peak 63’ and ‘Peak 66’ cases are acceptable at or above 95% - however several contingencies require SPS operation to achieve a 95% or greater voltage. The exception to this occurs in the ‘Peak 83’ case with stuck breaker contingencies, KT3L-1 or KT3L-2 at Maxcy’s Substation or Section 84 out of service. Due to the split 115 kV bus arrangement at Maxcy’s Substation, both stuck breaker contingencies will remove the Maxcy’s autotransformer. Maxcy’s KT3L-1 stuck breaker contingency will remove 115 kV Section 60 (Maxcys – Bowman Street), Section 67 (Maxcys – Detroit), and Section 80 (Maxcys – Highland). Maxcy’s KT3L-2 stuck breaker contingency will remove 115 kV Section 68 (Maxcys to Mason), Section 88 (Augusta East Side to Maxcys), and Section 84 (Winslow to Maxcys). Note that ISO New England does not consider these stuck-breaker outages in system operations, per ISO New England Operating Procedure OP-19, Transmission Operations. Therefore, the low voltages involving these stuck breaker contingencies are treated as a pre-existing condition, and for these contingencies post-project voltages cannot be any worse than pre-project (Phase I) voltages. An outage of Section 84 by itself will produce voltages in the Winslow – Waterville area almost as low as the Maxcy’s KT3L-2 stuck breaker. For this reason a new 16.2 MVAR capacitor bank must be installed at the Winslow 34.5 kV bus by CMP (in addition to the existing 9 MVAR capacitor bank). When these capacitors are in place, voltages for all three of these contingencies, once the Winslow – SD Warren SPS Undervoltage is operated, are equal to or greater than 95%. (See Appendix D: Exception Reports for Contongencies) One-line diagrams of all contingencies with the final pre-project secure dispatch with reasonably stressed system conditions can be found in Appendix B. 7.2 Initial 90 MW Redington Mountain Wind Farm post-project results The Redington Mountain Wind Farm was modeled as described in report Sections 2 and 3. The same base cases and contingencies were used as in the pre-project final base cases, adjusted to obtain stressed system conditions with a secure dispatch as described above; with the additional generation at Redington is dispatched against Wyman Hydro and Harris Hydro. From the initial base cases, it can be observed that the northwestern CMP 115 kV voltage profile is reduced with Redington generation replacing Wyman and Harris hydroelectric generation, which have more local voltage control due to their location and greater reactive power capacity. By dispatching of Wyman and/or Harris generation off-line against the increase in generation at Redington, this area loses some reactive support for which Redington, with its limited generator reactive capability at a more remote location, is not able to compensate. When comparing the pre-project cases to the post-project cases, the initial base cases show bus voltages at Wyman Hydro 1.4% lower in the light load cases and as much as 2.2% lower in the peak load cases as indicated in the one lines found in Appendix B.

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Redington Wind Farm 90 MW System Impact Study Page 25 January 10, 2006

Because Redington is only separated from Wyman and Harris generation by a radial transmission line, and because there is a MW-for-MW tradeoff of generation between these locations, no problems occurred with transmission line loading for any contingencies. In the post-project ‘Peak 63’ case, as in the same pre-project case, Section 86 from Bucksport to Belfast is slightly overloaded at 1% greater than its normal rating, indicating that the Orrington-south interface is at its transfer limit. The post-project ‘Peak 63’ case also illustrates the Maine-New Hampshire transmission interface is at its limit; with Section 250 from Louden to Maguire Road overloaded as much as 18% with the 345 Deerfield stuck breaker contingency. This is consistent with the corresponding pre-project case. The reduction in reactive support along with certain outages cause low bus voltages to appear in the post-project peak load cases. All post-contingent voltages are adequate in the light load cases. Bus voltages for the Maxcy’s stuck breaker KT3L-1 contingency are between 1% and 6% lower for the post-project case as compared to the pre-project case as illustrated below in Table 7-1. Other contingencies which result in voltages below 95% in the peak load cases, have low voltages occur in the same Waterville-Winslow-Skowhegan area, and in Guilford. Table 7-1:

Comparison of Voltage Performance Peak 83 Case with Maxcy’s 115 kV Stuck Breaker KT3L-1 Outage

Pre-project Post-project

without reinforcements

Post-project with

reinforcements

Pre- vs. Post-project

Post-SPS Post-SPS

base outage After base outage After base outage After w/out rein-forcements

with rein-forcementsBus

Name case case SPS case case SPS case case SPS Delta Delta LAKEWOOD 100% 95% 96% 95% 89% 90% 101% 95% 96% -6% 0%SDW SOMS 100% 94% 96% 95% 88% 90% 100% 94% 96% -6% 0%WINSLOW 101% 96% 96% 97% 89% 91% 101% 95% 96% -5% 0%GUILF GN 98% 96% 97% 97% 93% 93% 98% 96% 97% -4% 0%NORT AUG 102% 95% 95% 105% 93% 94% 101% 95% 95% -1% 0%PUDDLDK 102% 95% 95% 100% 93% 94% 101% 95% 95% -1% 0%AUG E S 102% 95% 96% 105% 93% 94% 101% 95% 96% -2% 0%BOWMAN 102% 96% 96% 101% 94% 95% 102% 96% 96% -1% 0% 7.3 Final 90 MW Redington Mountain Wind Farm post-project results, with Reactive Reinforcements There were no loading issues for any of the base cases with the Redington Mountain Wind Farm dispatched against Wyman and Harris hydroelectric generation. Low voltage issues occurred in all three of the peak cases. In each case, for several contingencies, the low voltages occurred in the same Waterville-Winslow-Skowhegan area, and also at Guilford (see Appendix D: Exception Reports). To alleviate these low voltages, additional reactive support needs to be added to compensate for the loss of reactive support from the displaced hydro units. An additional 7.2 MVAR of capacitors are required at Winslow Substation to expand one existing 9 MVAR bank to 16.2 MVAR for a total of 32.4 MVAR at Winslow Substation. (Subsequent sensitivity analysis discussed in section 8.3 of this report has determined this additional capacitance is CMP's responsibility.) At Lakewood Substation a new 10.8 MVAR of capacitor bank is required, and Guilford Substation requires an additional 5.4 MVAR for its existing capacitor bank. All 50

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contingencies listed in Section 7 were simulated with and without these reinforcements in the three peak cases. Without these reinforcements, voltages in that area fell below 95% for several contingencies. With these reinforcements, no voltage fell below 95% with any contingency. As shown in Table 7-1, low voltages for the Maxcy’s KT3L-1 stuck breaker contingency in the post-project ‘Peak 83’ case are now between 95% and 97%, which are within the acceptable limits. One-line diagrams of all contingencies with the final post-project dispatch, with reinforcement requirements to obtain adequate post-contingency voltages, are in Appendix B. 7.4 Kennebec River 345 kV Double Circuit Tower Contingency The Kennebec River double circuit tower contingency was simulated for all cases. This contingency removes Section 375 between Maine Yankee and Buxton and Section 377 between Maine Yankee and Surowiec, from service. All voltages for both the peak and light load cases were above 95% with the exception of two cases. The ‘Light 66’ case shows the voltage at the Surowiec 345 kV bus to be at 94% for both the pre-project and post-project corresponding cases. The ‘Light 83’ case shows the voltage at the Surowiec 345 kV bus at 93% for the 30 MW case and 94.5% for the post-project case. There were no loading issues for any of the peak load cases. The increased Maine load in these peak cases is utilizing the area generation so that 115 kV underlying flows are reduced and, there are not any overloads. The light cases consistently showed overloading on Section 81 from Mason to Topsham to Surowiec and on Section 207 from Mason to Maine Yankee to Bath - as expected. The ‘Light 66’ case showed the greatest overloads on Section 81 at 60% above its STE rating for the 30 MW case. Sections 81 and 207 overloads for the post-project cases are 1% to 2% lower than the pre-project cases, as shown in Appendix B. The voltage and loading results from this contingency show that there is no significant difference in the pre-project and the post-project cases and therefore Redington Mountain Wind Farm does not have an adverse effect with regard to this contingency. This contingency has received an exclusion from both NEPOOL and NPCC, per the ISO New England “Reliability Standards” and the NPCC “Basic Criteria.”

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8. Steady State Sensitivity Analysis Results 8.1 Northeast Reliability Interconnect (NRI) Project A Northeast Reliability Interconnect (NRI, also known as the 2nd New Brunswick Tie Project) sensitivity analysis was performed to demonstrate the steady state voltage and thermal effect on the system with the Redington Mountain Wind Farm project. Dispatch Redington was modeled with the Vestas V90 at 90 MW and the recommended capacitive reinforcements installed. The Peak 83 case was modified to obtain a New Brunswick – Maine interface transfer of 1,000 MW and an Orrington–South interface transfer of 1,200 MW with the NRI project in service. This was achieved by reducing generation in Maine while increasing generation in New Brunswick as shown in Table 8-1 and in Appendix C. Table 8-1: NRI Generation Dispatch Comparison

Generator P Max (MW)

Peak 83 Case (MW)

NRI Peak 83 Case

Bucksport G4 191 191 OFF Coleson Cove G3 (New Brunswick) 352 OFF 335 Great Falls GL (New Brunswick) 61 30.6 OFF MLT G1-2 (New Brunswick) 3.6 3.6 OFF Total 225.2 335 Results Both the Section 84 outage and the Maxcy’s KTL3-2 stuck breaker contingencies were used with the redispatched ‘Peak 83’ case with the above modifications. These contingencies were chosen since they were the most severe contingencies along the MEPCO corridor where the NRI project interconnects; and they produced the lowest voltages with the ‘Peak 83’ case. A voltage comparison between the NRI base case and the outages can be seen below. There are no loading or voltage violations for either contingency. Results show that Redington Mountain Wind Farm interconnection has no significant impact on the proposed NRI project.

NRI Voltage Results 1000 MW New Brunswick–Maine Transfer

Peak 83 Case, Vestas V90 at 90 MW with Reinforcements

Table 8-2: Base (%) Sec 84 OOS (%) SB Maxcys KT3L-2 (%) SD Warren 99 96 96 Sect. 83C Tap 102 96 96 Winslow 100 96 96 Prides Corner 98 98 98 Guilford 98 99 99 Wyman 100 99 97

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8.2 Line Y138 Closing Project A sensitivity analysis was performed which demonstrates the steady state voltage and thermal effect on the system with the Y138 Closing Project and Redington Mountain Wind Farm operational. Dispatch Redington was modeled with the Vestas V90 at 90 MW and the recommended capacitive reinforcements installed. The ‘Peak 63’ case was modified to stress Western Maine and Northern Hydro generation and transfers as much as possible with the Y138 project in service. This was achieved by maximizing the generation north of the Surowiec-South transmission interface as shown in Table 8-3 below, while keeping the Maine-New Hampshire transmission interface below its thermal limit (See Appendix C). In addition W. F. Wyman units 1 and 3 (57 MW and 125 MW respectively) were switched off to maintain Maine-New Hampshire transfers. Table 8-3: Steady State Western Maine Generation

Generator

P Max (MW)

Peak 63 Case (MW)

Stressed Western Maine Pak 63 Case

AEC G1 57.7 37 56 AEC G2 57.7 37 56 AEC G3 57.7 OFF 56 Sub - Total 74 168 RPA CG1 179 176 176 RPA SG293.5 94 90 90 Sub - Total 266 266 AEI 39 OFF 39 Mead CoGen 110 93 110 Total 433 583 Results The re-dispatched Peak 63 case with the above modifications was simulated with the full set of contingencies. Results showed there were no overloads or voltage violations. (See Appendix B: One-Line Diagrams). Results of other contingencies in the Maine-New Hampshire transmission interface 345 kV corridor indicate local overloads in New Hampshire only. Based on these results the Y138 Line Closing Project has no adverse impact on the Redington Mountain Wind Farm Project. 8.3 Upper Kennebec Dispatch The generation in the Upper Kennebec area of the 30 MW ‘Peak 63’ Case was re-dispatched to correspond to that of the post-project ‘Peak 83’ case. This illustrates whether the contributing factor to the low voltages is the dispatch used for the Redington cases or the additional Redington generation. The Wyman and Harris dispatch from the post-project case provide more severe results for the pre-project case, than the stressed dispatch to obtain maximum transfers. See Table 8-4: Upper Kennebec Generation Sensitivity.

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Table 8-4: Upper Kennebec Generation Sensitivity

Generator

90 MW

Pre-project

Re-dispatched Pre-project

Harris 1 16.8 16.8 16.8 Harris 2 OFF 35.0 OFF Harris 3 OFF OFF OFF Wyman 1 20.0 20.0 20.0 Wyman 2 20.0 20.0 20.0 Wyman 3 OFF 25.0 OFF Redington 90.0 30.0 30.0

Line Section 84 was taken out of service on the re-dispatched case and the results were compared with the original pre-project and post-project cases with the Section 84 contingency. The results can be seen in the first three data columns of Table 8-5: Upper Kennebec Dispatch Voltages.

Table 8-5: Upper Kennebec Dispatch Voltages (%)

Original Pre-project

Original Post-project

Pre-project –New Dispatch

Pre-project w/added capacitors New Dispatch

Winslow 96 96 93 96 SD Warren 96 96 94 96 83 C Tap 96 96 94 96 Lakewood 97 97 94 97 83 B Tap 97 97 95 97 Guilf. Gen 98 99 98 98 Wyman 100 100 100 100

The re-dispatched case shows voltages below 95%. In addition to the 16.2 MVAR capacitor bank discussed in Section 7.1, by adding an additional 7.2 MVAR of capacitance at Winslow (upgrading the present 9 MVAR to 16.2 MVAR for a total of 32.4 MVAR) the voltages are raised to acceptable limits in the redispatched pre-project case, as illustrated in the 4th data column of Table 8-5: Upper Kennebec Dispatch Voltages.

The results indicate that the reduced transfers from the redispatch did not unstress the northern CMP 115 kV system enough to compensate for the reduction in MVAR capabilities. With additional reactive compensation, by expanding the existing Winslow Substation capacitor bank from 9 MVAR to 16.2 MVAR for a total of 32.4 MVAR, the results are acceptable. Therefore, this becomes CMP’s requirement rather than a Redington project requirement.

8.4 Livermore Falls Stuck Breaker Sensitivity A second contingency was performed which isolates only the Livermore Falls Substation 115 kV bus. The original model simulates the lack of bus differential protection at Livermore Falls for a bus fault, by opening remote breakers through zone 2 protection. However, since breaker failure protection exists at Livermore Falls Substation, a contingency was simulated on the post-project ‘Peak 63’ case to represent a stuck breaker at Livermore Falls other than the Section 63 breaker. As seen in Table 8-6:Livermore Falls Stuck Breaker Sensitivity – Voltages (%), voltages are low for the post-project case as compared to the pre-project case and the voltage at Sturtevant falls below acceptable levels. The third column, “pre-project Case – New Dispatch” has the Livermore Bus isolated under post-project generation dispatch, i.e. Wyman and Harris generators are modeled as they are in the post-project case (see Section 8.3: Upper Kennebec Generation). Even with this dispatch the voltages are at

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acceptable levels “pre- Redington”. A 5.4 MVAR capacitor bank was modeled at Sturtevant, which provided acceptable voltages in the area. Table 8-6: Livermore Falls Stuck Breaker Sensitivity – Voltages (%)

Post-project w/ Reinforcements

Pre-project Original Dispatch

Pre-project

New Dispatch

Post-project w/Reinforcements

& Sturtevant Capacitor Sturtevant 94 96 95 96 Prides Corner 98 98 98 98 Williams 98 100 100 99 Guilford 99 98 98 99 Rice Rips 99 99 99 99

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9. Transient Performance Criteria

9.1 Contingencies Stability results were analyzed using the criteria in the Reliability Standards for New England Power Pool, (Planning Procedure 3), January 2004. Low voltage ride through criteria was based on the third draft of the Generator Low Voltage Ride Through Criteria by the NEPOOL Stability Task Force dated August 3, 2005. Normal Contingencies The following normal contingencies, as defined by Reliability Standards of the New England Power Pool (Planning Procedure #3), were considered for this analysis. a. Permanent 3-phase fault on any generator, transmission circuit, transformer or bus section, with

normal fault clearing. b. Simultaneous permanent phase-to-ground faults on different phases of each of two adjacent

transmission circuits on a multiple-circuit transmission tower, with normal fault clearing. If multiple circuit towers are used only for station entrance and exit purposes, and if they do not exceed five towers at each station, then this condition and other similar situations can be excluded on the basis of acceptable risk, provided that NEPOOL specifically approves each request for exclusion. The NPCC Reliability Coordinating Committee must grant similar approval.

c. Permanent phase-to-ground fault on any transmission circuit, transformer, or bus section with delayed fault clearing.

d. Loss of any element without a fault. e. Permanent phase-to-ground fault in a circuit breaker with normal fault clearing. f. Simultaneous permanent loss of both poles of a direct current bipolar facility without an ac fault. g. Failure of any Special Protection System (SPS) which is not functionally redundant following the

contingencies listed in “a” through “f” above. h. The failure of a circuit breaker associated with an SPS following: loss of any element without a

fault; or a permanent phase to ground fault, with normal fault clearing, on any transmission circuit, transformer, or bus section.

The following criteria define stable transmission system performance for normal contingencies.

• All units transiently stable except for units tripped for fault clearing. • A 50% reduction in the magnitude of system oscillations must be observed over the last four

periods of the oscillation. • Loss of source not greater than 1,200 MW. • No entry of the Keswick GCX apparent impedance relay characteristic on Section 396/3001

line from Keswick to Orrington at Keswick S/S. Extreme Contingencies The Reliability Standards also address extreme contingencies that are considered more severe than a normal contingency but have a lower probability of occurrence. The transmission bulk power system performance in response to an extreme contingency is intended to be a gauge of the system’s robustness or a measure of the extent of the disturbance. The following extreme contingencies, as defined by Reliability Standards will be considered for this analysis: a. Loss of the entire capability of a generating station.

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b. Loss of all lines emanating from a generating station, switching station or substation. c. Loss of all transmission circuits on a common right-of-way. d. Permanent three-phase fault on any generator, transmission circuit, transformer or bus section,

with delayed fault clearing and with due regard to reclosing. This delayed fault clearing could be due to a circuit breaker, relay system or signal channel malfunction.

e. Sudden dropping of a large load or major load center. f. The effect of severe power swings rising from disturbances outside New England g. Operation or partial operation of Special Protection for and event or condition for which it was

not intended to operate. Of the seven types of extreme contingencies which were considered, the NEPOOL Stability Task Force (STF) typically focuses on permanent three-phase stuck breaker faults with delayed clearing, detailed in bullet d) above. The STF has indicated measures that should be used to determine acceptable and unacceptable system performance resulting from this type of fault. The following responses are considered acceptable: • A 50% reduction in the magnitude of system oscillations observed over four periods of the

oscillation. • Loss of source up to 1,400 MW. • A loss of source greater than 1,400 MW is not immediately acceptable. • A loss of source between 1,400 MW and 2,200 MW may be acceptable depending upon the

likelihood of occurrence and other factors. The following responses are considered unacceptable: • Transiently unstable with wide spread system collapse. • Transiently stable with undamped or sustained system oscillations. • Loss of source greater than 2,200 MW. Oscillatory Response All design contingencies, both normal and extreme, shall meet the “ISO New England Damping Criteria” which states; “Acceptable damping with time domain analysis requires running a transient stability simulation for sufficient time (up to 30 seconds) that only a single mode of oscillation remains. A 50% reduction in the magnitude of the oscillation must then be observed over four periods of the oscillation. A sufficient number of system quantities including rotor angle, voltage, and interface transfers should be analyzed to ensure that adequate system damping is observed.” [NEPOOL Stability Task Force submittal, August 18, 1999]. Low Voltage Ride Through Criteria The basic criterion for generator low voltage ride through capability is that for all design contingencies, for which the clearing of the disturbance does not require disconnecting the generator, the generator must stay connected to the transmission system and not cause a significant adverse effect to the transmission system. Design contingencies are described in the ISO New England Planning Procedures (reference PP 5-3, etc.). Specifically, the low voltage ride through requirements vary depending on where the fault is located on the transmission system as follows:

a. For design contingencies on the BPS, the unit must stay synchronized when the simulation is based on fault clearing initiated by the “system A” protection group, and also shall be maintained when the simulation is based on fault clearing initiated by the “system B” protection group.

b. For design contingencies on the non-BPS, the unit must stay synchronized when the simulation is based on either fault clearing initiated by the “system A” protection group, OR when the simulation is based on fault clearing initiated by the “system B” protection group. This ride through capability may be attained either by enhanced capability in the generator or faster clearing times, or both.

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9.2 Bulk Power System Testing Given the remote site location and the relatively small amount of generation that has been proposed for the Redington Mountain Wind Farm site, no Bulk Power System Testing is required for this study. 9.3 Short Circuit Analysis The short circuit analysis modeled the wind turbine generators as variable-speed wound-rotor induction machines capable of contributing rated short circuit current to the low voltage (1000 kV) windings of the generator step-up transformers. Step-up transformation was modeled with the manufacturer’s specified impedance.

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10. Transient Analysis Study Methodology

The dynamic stability analysis was performed using General Electric’s PSLF software package, Version 15. The Vestas V90, 90 MW wind turbine was modeled according to the “Advanced Grid Option 2, V90 VCRS – 3.0 MW” preliminary documentation dated October 4, 2004, and documentation regarding Low Voltage Ride Through (LVRT) for the Vestas V90, dated October 26, 2005, which was provided by Vestas, the turbine manufacturer (see Appendix F). Additional modeling details, specific to PSLF, were provided by EnerNex Corporation via a memorandum, “Modeling the Vestas V90 Wind Turbine in GE PSLF – Version 1”, from Bob Zavidil (EnerNex Corporation) to Steve Saylors (Vestas) dated July 18, 2005. (See Appendix G) This model was tested by CMP to determine whether the model would provide a reasonable machine response to a severe local contingency. It did. CMP cannot verify model accuracy for the manufacturer’s equipment. The purpose of the analysis is to determine the effect, if any, that interconnecting 90 MW at the Nash Stream Substation has on the transient and dynamic performance of the CMP and New England System in response to a number of different disturbances. 10.1 Fault Contingency Descriptions Table 10-1: Transient Fault Contingency Summary – Three-phase Faults, and Table 10-2: Transient Fault Contingency Summary - Single Line-to-Ground Faults, provide a description of the faults which were used to analyze the impact of the Redington Mountain Wind Farm Project on local and system wide stability performance.

Table 10-1: Transient Fault Contingency Summary – Three-phase Faults

Type

ID Sect

#

Fault

Location

Fault Type

Stuck Breaker

Faulted Element

Tripped Element

Clearing Time (cycles)

NC 3P66S 66

Wyman Hydro 115 kV Three-phase None

Wyman Hydro– Detroit

Wyman Hydro K66-1 Detroit K66-6

7 6

NC 3P83 83

Wyman Hydro 115 kV Three-phase None

Wyman Hydro– Winslow

Wyman Hydro K83-5 Winslow K83-1

5 8

NC 3P63 63

Wyman Hydro 115 kV Three-phase None

Wyman Hydro– Livermore Falls

Wyman Hydro K63-1 Livermore Falls K63-2

7 9

NC 3P396 396 Keswick 345 kV

Three-phase None

Keswick-Orrington

Orrington K396-1, K396/388 Keswick: K3-6, K3-5

4 4

NC 3P385 385 Buxton 345 kV

Three-phase None

Buxton-Deerfield

Buxton K385-1 Buxton K385/374 Deerfield 851 Deerfield 785

4 4 5 5

EC 3P357

357

West Medway 345 kV

Three-phase, with a Stuck

Breaker

W. Medway 105 (IPT)

W. Medway to Milbury

W. Medway 104 Milbury 4357 Milbury 302 W. Medway 106 Bridgewater 1680 Bridgewater 1690

4 4 4 10.25 10.25 10.25

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Table 10-2: Transient Fault Contingency Summary - Single Line-to-Ground Faults

Type

ID Sect

#

Fault

Location

Fault Type

Stuck Breaker

Faulted Element

Tripped Element

Clearing Time (cycles)

NC 1P203

S 203 Detroit 115 kV

Single Line–to-Ground stuck

breaker Detroit K203-1

Detroit – Bucksport

Bucksport K203-2 Maxcy’s K67-4 Wyman Hydro K66-1

6 62 62

NC 1P63a 63

Wyman Hydro 115 kV

Single Line- to-Ground Stuck

Breaker

Wyman Hydro K63-1

Wyman Hydro – Livermore Falls

Livermore Falls K63 –2 Wyman Hydro K83-5 Wyman Hydro K66-1 Wyman Hydro K222-1 Wyman Hydro KG1, KG2, & KG3

9 20 20 20 21

NC 1P200 200

Livermore Falls

115 kV

Single Line–to-Ground stuck

breaker

Livermore Falls K200-4

Livermore Falls – Gulf Island

Gulf Island K200-12 AEI K200A-3 Livermore Falls K63-2, Livermore Falls K89-1

6 9 19 19

NC 1P66 66

Wyman Hydro 115 kV

Single Line- to-Ground Stuck

Breaker

Wyman Hydro K66-1

Wyman Hydro– Detroit

Detroit K66-6 Wyman Hydro K83-5 Wyman Hydro K63-1 Wyman Hydro K222-1 Wyman Hydro KG1, KG2, KG3

5 20 20 20 21

NC 1P84 84 Winslow 115 kV

Single Line–to-Ground stuck

breaker Winslow K84-1

Winslow- Maxcy’s

Maxcy’s K84-2 Winslow K83-1

8 21

NC 1P83 83

Wyman Hydro 115 kV

Single Line- to-Ground Stuck

Breaker

Wyman Hydro K83-5

Wyman Hydro – Winslow

Winslow K83-1 Wyman Hydro K66-1 Wyman Hydro K222-1 Wyman Hydro K63-1 Wyman Hydro KG1, KG2, KG3

5 20 20 20 21

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11. Transient Analysis Results

The comparison discussion of the fault results is limited to the Redington generator busses and the Bigelow 115 kV (point of interconnection) for voltage. The angle observations are limited to SEA, Wyman Hydro and Harris. The result of the transient analysis is that the interconnection of Redington Mountain Wind Farm at 90 MW has no adverse effect on the system. Voltage and angle plots can be found in Appendix H. For voltage plots, Redington OFF and ON must be identified by the color of the graph: Redington OFF in BLUE and Redington ON in GREEN. Note that the color in the plot legend is correct, but the tick marks are not correct. For the machine angle plots, Redington OFF and ON can be identified by the tick marks: Redington OFF tick marks are noted by an "a", Redington ON tick marks are noted by a "b", in the legend. 11.1 Transient Three-phase Fault Results Table 11-1: Transient Three-phase Fault Result Summary provides a description of the system performance resulting from fault simulations as described in Table 10-1: Transient Fault Contingency Summary – Three-phase Faults. As seen from the Fault Result Summary, all faults were stable with the 90 MW contribution from Redington Mountain Wind Farm, with the exception of the three-phase stuck-breaker extreme contingency fault on Section 357. The three-phase faults on Section 63, Section 66, and Section 83 were applied at the Wyman Hydro bus, electrically the same location for each fault, but each with a different post-fault system configuration. For the Section 83 fault, the damping appears the same with Redington ON or OFF. As seen from the plot results, the Section 66 fault system response appears to be unstable with Redington OFF, but stable with Redington ON. This has been observed in other studies. This is attributed to the modeling of the Harris generators (Harris units 2 & 3 have no excitation system model). With all three generators on, G1 remains on line while G2 and G3 lose synchronism. Unfortunately this modeling issue cannot be corrected until additional generator data is obtained for the Harris Hydro units. With Redington ON, this fault on Section 66 is stable since Redington is dispatched against one of the three Harris generators. With Redington ON, the results of this fault are quite similar to those of Section 83. As seen in Table 10-1: Transient Fault Contingency Summary – Three-phase Faults, clearing times for a three-phase fault on Section 63 are 7 cycles for Wyman Hydro breaker K63-1 and 9 cycles for Livermore Falls breaker K63-2. With Wyman Hydro K63-1 breaker clearing time modeled at 7 cycles, this fault results in all three Harris Hydro generator units losing synchronism, with Redington OFF. The fault was modeled again substituting 6-cycles for the-7 cycle clearing time at the Wyman Hydro end of Section 63. With this shorter clearing time, the fault results are stable and the damping is the same with both Redington OFF and ON. Therefore, a breaker with a faster clearing time may be required at the Wyman Hydro end of Section 63, pending further investigation of this fault with accurate excitation system models for all of the Harris generators. If required, a faster breaker would be CMP’s responsibility.

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Table 11-1: Transient Three-phase Fault Result Summary

Type

Redington OFF

Redington ON

Comments

NC 3P66S Harris

Unstable

Stable

All other generators are stable when Redington is dispatched against one of the three Harris generators. See three-phase fault results.

NC 3P83 Stable

Stable Damping is the same with Redington ON and OFF

NC 3P63 Stable

Stable

Both ON and OFF conditions require a maximum 6 cycle clearing time at Wyman K63-1 breaker.

NC 3P396 Stable

Stable Damping is the same with Redington ON and OFF

NC 3P385 Stable

Stable

Damping is the same with Redington ON and OFF. Both ON and OFF conditions require a maximum 1,400 MW ME-NH interface.

EC 3P357 Unstable

Unstable

Damping slightly better with Redington ON. Both ON and OFF conditions require a maximum 1,400 MW ME-NH interface.

The three-phase fault on Section 396 shows damping to be the same with Redington OFF or ON. A three-phase normally-cleared fault at Buxton on Section 385, and a three-phase stuck-breaker fault at West Medway on Section 357, required the interface flow between Maine and New Hampshire to be reduced from 1,700 MW to 1,400 MW with Redington ON or OFF. This is consistent with the results obtained in the “Y138 Closing Study.” The interface was reduced to approximately 1,400 MW to enable an acceptable system response. Discussions with ISO-New England validated the 1,400 MW ME-NH interface transfer as acceptably stressed under these conditions. With this new dispatch, with a three-phase fault on Section 385, damping is slightly better with Redington ON. For a three-phase stuck-breaker extreme contingency fault at West Medway on Section 357, the system is unstable. Under the base conditions, the system separates about 1.7 seconds after the fault between northern Maine and southern Maine, near Bangor, along the Orrington-south interface (345 KV Section 388 and 396, and 115 KV Sections 86 and 203 trip) for this extreme contingency. Details of this fault are approximately the same with Redington OFF or ON, as seen in Table 11-2: Section 357, Three-phase Stuck-breaker Fault Summary. The one line diagrams for this contingency are found in Appendix H. Redington Mountain Wind Farm does not have any significant adverse impact to the system for this extreme contingency. Table 11-2: Section 357 Three-phase Stuck-breaker Fault Summary

Redington OFF t = seconds

Redington ON t = seconds

Occurrence

0.1 0.1 Fault Applied 1.483 1.475 Opened Section 86 and Section 203

(Bucksport Overcurrent SPS operation)1.741 1.754 Opened Section 388 (step distance) 1.817 1.808 Opened Section 396 (step distance)

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11.2 Single Line-To-Ground Fault Results Table 11-3: Single Line-to-Ground Fault Result Summary, provides a description of the system performance resulting from fault simulation as described in and Table 10-2: Transient Fault Contingency Summary - Single Line-to Ground Faults. Voltage and angle plots can be found in Appendix H. Table 11-3: Transient Single Line-to-Ground Fault Result Summary

Type

Redington OFF

Redington ON

Comments

NC 1P63a Stable Stable

NC 1P66P Stable

Stable NC 1P83 Stable Stable

Island formation: Sect. 222/82 with Harris over-speed protection Sect. 63/215 with SEA and Redington SEA over-speed unknown, otherwise transfer trip

NC 1P84 Stable

Stable NC 1P200 Stable Stable

NC 1P203S Stable

Stable Better damped with Redington ON

Voltages When a single line-to-ground fault was applied to Section 63, Section 66, or Section 83, with a stuck breaker on the Wyman Hydro end, the results were almost identical with or without Redington interconnected to the system. For the remaining single line-to-ground faults, because the fault location is electrically far away from the Redington site, the voltage sags at the generator terminal are barely noticeable. For all these faults on Section 84, Section 200 and Section 203, the transient voltage sag on the Bigelow 115 KV bus is less than 20% of nominal voltage. The worst transient voltage sag of these faults occurs on Section 203. Angles Although mild in both amplitude and duration for all single line-to-ground stuck-breaker faults, the angle oscillations are slightly more pronounced in the 1P203S fault. As seen in Table 10-2: Transient Fault Contingency Summary - Single Line-to Ground Faults, 1P203S has a fault duration approximately three times greater than the other faults while the electrical proximity to the Redington site is comparable. None of the faults come close to causing a trip of the Redington generators either at the generator terminals or the point of interconnection.

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12. Transient Sensitivity Analysis

12.1 Northeast Reliability Interconnect (NRI) and Line Y138 Closing Project This study was based on the generation dispatch described in Section 5.4. All faults were run on cases with Redington Mountain Wind Farm in service.

Table 12-1: Transient Fault Contingency Summary – NRI & Y138 Sensitivity

Type

ID

Base Case Redington

ON

With NRI and Y138

projects Redington ON Comments

NC 3P63 Stable Stable No significant difference NC 3P66_S Stable Stable No significant difference NC 3P83 Stable Stable No significant difference

NC 3P385b Stable Stable

The base case required a maximum 1,400 MW ME-NH transfer. With NRI & Y138 in service, the interface was modeled above 1,700 MW with a stable result.

NC 3P396 Stable Stable Damping improves slightly with NRI & Y138 projects in service.

EC 3P357 Unstable Unstable

With NRI &Y138 in service, the system breaks apart at the ME-NH interface instead of the Orrington-South interface.

NC 1P63a Stable Stable No significant difference. NC 1P66P Stable Stable No significant difference. NC 1P83 Stable Stable Slightly less damping with NRI & Y138 in service. NC 1P84 Stable Stable No significant difference. NC 1P200_LF Stable Stable No significant difference. NC 1P203S Stable Stable No significant difference.

All base cases have a 1700 MW ME/NH interface except 3P357 and 3P385b which have a ME/NH interface of 1400 MW. With the NRI and the Y138 Closing Project in service, the interface was modeled at over 1,700 MW, consistent with the Y138 Closing Project Study. For a three-phase fault on Section 385 with Redington Mountain Wind Farm in service, the Maine-New Hampshire interface can not be grater than 1,400 MW. With these projects in place, the initial fault recovery time is slightly better; however the damping recovery is slightly worse with the 300 MW of additional ME-NH transfer.

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For a three-phase stuck-breaker extreme contingency fault at West Medway on Section 357, the system is unstable:

• Under the base conditions, the system separates about 1.7 seconds after the fault between northern Maine and southern Maine, near Bangor, along the Orrington-south interface (345 KV Section 388 and 396, and 115 KV Sections 86 and 203 trip) for this extreme contingency. The equivalent loss-of-source to the eastern interconnected systems for this contingency is 970 MW.

• Under the sensitivity condition with the NRI and Y138 projects in service, the system breaks apart about 1.9 seconds after the fault in southern Maine, along the Maine-New Hampshire interface (345 KV Section 385 and 391, and 115 KV Sections 224, and 250 and Y138 trip) for this extreme contingency. The equivalent loss-of-source to the eastern interconnected systems for this contingency is 1820 MW.

The equivalent loss-of-source to the eastern interconnected systems was determined by summing the measured pre-contingency flows on the lines which tripped to cause system separation. The three-phase fault on Section 396 was modeled with the “Section 396 SPS” in service, designed to trip the Maine Independence Station generators when the Keswick-Chester-Orrington 345 KV line (Section 396) is opened. Damping improves slightly with the NRI and Y138 Closing Project in service. In conclusion, this sensitivity shows that the NRI and Y138 projects have no adverse effect on the interconnection of the 90 MW wind farm, nor does the wind farm have any adverse effect on the projects. The most significant results of this study show that with the projects in service, 1) the system can withstand a three-phase fault on Section 385 with the Maine–New Hampshire Interface greater than 1,700 MW and 2) with a three-phase fault on Section 357, the system will separate at the ME-NH interface instead of the Orrington-South interface, with an increased loss-of-source to the eastern interconnected systems. 12.2 Light Western Dispatch This sensitivity was based on the generation dispatch described in Section 5.4. All faults were run on cases with Redington Mountain Wind Farm in service. These sensitivities were conduced to evaluate the Low Voltage Ride-Through (LVRT) capabilities of the V90 turbine-generators when there is less generation in the local area to sustain the voltage. Although for the three-phase fault cases the post-fault voltage dipped lower than cases with more generation dispatched in the immediate area, the ride-through capability of the generator met the LVRT criteria.

Table 12-2: Transient Fault Contingency Summary – Light Western Maine Dispatch Sensitivity

Type Fault

ID Base Case

Light

Western Generation Comments

NC 3P63 Stable Stable Fault voltage drops lower with light generation. NC 3P66_S Stable Stable Fault voltage drops lower with light generation.

NC 3P83 Stable Stable Fault voltage drops lower with light generation. Damping improves slightly.

NC 1P84 Stable Stable No significant difference. NC 1P200 Stable Stable No significant difference. NC 1P203S Stable Stable No significant difference.

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13. Short Circuit Protection The short circuit analysis modeled the wind turbine generators as variable-speed wound-rotor induction machines capable of contributing rated short circuit current to the low voltage (1000 kV) windings of the generator step-up transformers. Step-up transformation was modeled with the manufacturer’s specified impedance. Table 13-1: Short Circuit Fault Study illustrates that the short circuit duties were found to be within the ratings of the existing 34.5 KV and 115 KV system equipment. No adverse short circuit impact was found as a result of interconnecting Redington Mountain Wind Farm. Table 13-1: Short Circuit Fault Study

Substation Base System With Redington

Rated Comment

kV 3LG kA

1LG kA

3LG kA

1LG kA kA

Redington 115 3.96 1.67

Bigelow 115 3.30 1.87 4.59 2.09 10Stratton Energy 115 3.03 1.60 3.89 1.73 10

Wyman Hydro 115 8.09 7.70 8.68 8.05 6

K215-1 Overdutied in Base System & with Redington *

Embden 115 6.31 5.20 6.54 5.30 10Williams Hydro 115 6.00 4.95 6.21 5.04 17Madison Paper 115 5.62 3.63 5.71 3.65 7

Sturtevant 115 6.02 4.03 6.05 4.04 10

Moscow 115 4.48 3.70 4.63 3.77 7

Harris Hydro 115 3.06 3.40 3.10 3.43 17

Hartland 115 5.36 3.53 5.43 3.55 10

Detroit 115 6.13 3.91 6.18 3.92 7

Lakewood 115 4.63 2.76 4.68 2.77 40

Redington 34.5 12.55 14.33

Bigelow 34.5 2.15 2.35 2.26 2.44 8

Stratton 34.5 1.42 1.24 1.47 1.26 10Basis: 1. Bus fault duty kA rms symmetrical 2. Interrupting rated kA rms symmetrical 3. Aspen case jul05.olr * The cost to replace the existing over-dutied circuit switcher, K215-1, with a one having adequate capacity, has been credited to Endless Energy against the Wyman Substation portion of this project.

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13.1 Protection Analysis The following information summarizes the protection requirements for the connection of 90 MW of generation onto Section 215 at Bigelow Substation: Protection Summary 1. 115 KV Section 215 is tapped onto Section 63 at Wyman Hydro Substation through a circuit switcher K215-1. Section 215 supplies a fused transformer at Bigelow Substation and connects to Section 215A, which provides a connection to the Stratton Energy plant. 2. The existing Section 215 primary protection at Wyman Hydro consists of electro-mechanical non-directional overcurrent relays and a single distance relay that are supplied from a set of in-line current transformers on the Section 215 tap. The primary relaying trips circuit switcher K215-1. 3. The Section 215 backup protection is provided by slow-clearing non-directional overcurrent relays on the K63-1 breaker. The backup relaying trips breaker K63-1. 4. There is an existing transfer trip carrier that trips the Stratton Energy plant on a K215-1 "b" contact or relay operation. Protection Recommendations 1. In order for the Section 215 line rating to increase to the 212°F limit of approximately 135 MVA, the relaying should be changed from overcurrent to step distance/directional ground overcurrent. This should be designed to CMP’s current 115 KV protection standards, which would require primary and backup digital protection relays supplied from separate current transformers. 2. The existing Section 215 primary overcurrent relays could misoperate for a close-in Section 63 fault because of infeed from the Section 215 generation. This should be corrected as listed in (1) above. 3. In order to provide high speed and dedicated fault clearing for Section 215, the backup overcurrent protection on the K63-1 breaker should be removed and Section 215 should be connected to the Wyman Hydro bus through a new 115 KV breaker. The K63-1 breaker should not be required to operate for Section 215 faults. 4. The existing transfer trip carrier that trips the Stratton Energy plant for K215-1 opening should be modified to include a trip of the Redington Wind Farm generation. This will minimize the chance for wind farm generation to be islanded with CMP Bigelow customers on a Section 215 fault. This new breaker will replace the current K215-1 circuit switcher, see Figure 4. Since the current K215-1 is currently overdutied in the base case, it is CMP’s responsibility to replace this circuit switcher. With the interconnection of Redington Mountain Wind Farm, Endless Energy will be credited the amount of a new circuit switcher towards the required new breaker. 5. A 115 KV breaker should be added at Bigelow Substation to connect the Redington Wind Farm site. This breaker should be provided with CMP’s standard 115KV primary and backup digital relaying to limit the effect on CMP’s customers for a fault on the new Redington 115 KV transmission line. 6. The Redington 115/34.5 KV transformer should be provided with CMP’s standard protection package for a transformer of this size and voltage, which is primary transformer differential and backup high-side overcurrent.

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14. Conclusions & Recommendations Based on the steady state analysis described in report Sections 7 and 8, a total of 40 MVAR of capacitor additions at Winslow, Lakewood, and Guilford Substations’ 34.5 KV busses, are required to obtain acceptable performance for all system conditions which were tested. The following are the interconnection requirements and cost estimates to interconnect the Redington Mountain Wind Farm 90 MW project, and avoid any significant adverse impact to the CMP and NEPOOL systems: Endless Energy Responsibility - $3,200,000 • Bigelow Substation: Expand yard, add a 115 KV bus, breaker, and control house - $1,510,000 • Wyman Substation: Separate Section 215 from 63, terminate with a breaker - $660,000* • Section 215 Transmission Line: Re- rate to 212o F - $300,000

• Lakewood Substation: Add a new 10.8 MVAR capacitor bank - $370,000

• Guilford Substation: Expand the existing 5.4 MVAR capacitor bank to 10.8 MVAR - $140,000

• Sturtevant Substation: Add a new 5.4 MVAR capacitor bank. - $220,000

* The $50,000 cost to replace the existing over-dutied circuit switcher K215-1, with a one having adequate capacity, has been credited to Endless Energy against the Wyman Substation portion of this project.

CMP Responsibility • Winslow Substation: Expand the existing capacitor bank from 9 MVAR to 16.2 MVAR • Winslow Substation: Add a new second 16.2 MVAR capacitor bank • Wyman Substation: subject to further review with accurate Harris & Wyman Hydro generator

models, replace breaker K63-1 The application of these capacitors at 34.5 kV both reduces the cost of reactive compensation and increases its effectiveness by also reducing the local 115/34.5 kV transformer reactive power losses. No upgrades are required to address impacts due to transient stability performance. With the interconnection reinforcement requirements, there is a reduced likelihood of operation of the Winslow SPS. This is demonstrated in Appendix D. With these interconnection requirements, the Redington Mountain Wind Farm 90 MW project meets the ISO New England Reliability Standards and the Minimum Interconnection Standard. There are no relevant queued resources ahead of Redington Mountain Wind Farm.